Many male arthropods package their sperm in a spermatophore for transfer to the female. We propose to analyze the structure, composition, and formation of the spermatophore of a model insect, Tenebrio molitor. We have previously described the development of the glands which make the wall of the spermatophore. These glands export a heterogenous structured product which is molded into the multi-layered wall of the spermatophore within the male reproductive tract. After its ejection from the male aedeagus, the spermatophore goes through a programmed sequence of expansions and bursts to release its seminal contents. The structure of the spermatophore will be investigated by differential interference contrast, histochemistry, and electron microscopy, with particular attention to the changes in the layers and their properties as the expansions take place. In some ways, the spermatophore is like cuticle without chitin. There are over/15 structural proteins in the wall of the spermatophore. In order to follow the formation and expansion of the spermatophore, we need specific probes for some of the proteins of the wall. The protein constituents of the spermatophore can be studied best with probes for specific proteins of the wall. We will prepare monoclonal antibodies to wall proteins by fusion of spaenic lymphocytes from BALB/c mice with myeloma X63/Ag 8.653. Clones will be screened by ELISA and then characterized further by immunoprecipitation and electrophoresis. Specific antibodies will be coupled with enzymes or fluorochromes for immunocytochemical localization of wall components. In the future, we can use these antibodies to isolate the structural proteins of the spermatophore, and we can extend our model study to other species such as Simulium, Culicoides, or Glossina, the vectors of filariasis, blue tongue virus, and trypanosomes, respectively. Increased knowledge of the reproductive biology of these vectors may aid in the development and evaluation of programs for their control.